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Biomedical subjects

A P Dwyer

Publications and source records attributed to A P Dwyer.

18 recordsLinked to original sources
PubMed2001

Vertebral osteomyelitis due to infection with nontuberculous Mycobacterium species after blunt trauma to the back: 3 examples of the principle of locus minoris resistentiae.

Osteomyelitis due to infection with nontuberculous mycobacterial organisms is unusual, especially in the absence of nonpenetrating trauma. We describe 3 patients with vertebral osteomyelitis due to infection with nontuberculous mycobacterial organisms that was precipitated by blunt trauma; these 3 unusual cases illustrate the principle of locus minoris resistentiae.

Adolescent↗
PubMed1998

Interobserver reliability of detecting lumbar intervertebral disc high-intensity zone on magnetic resonance imaging and association of high-intensity zone with pain and anular disruption.

STUDY DESIGN: Retrospective analysis of a spine imaging center's records of patients with chronic low back pain referred by tertiary care facilities. OBJECTIVES: 1) To assess the interobserver reliability of detecting lumbar intervertebral disc high-intensity zone on T2-weighted magnetic resonance imaging, and 2) to assess the relation between high-intensity zone and discography or post-computed tomography in symptomatic patients with low back pain. SUMMARY OF BACKGROUND DATA: Two of the three previous studies on this subject found an association between high-intensity zone and the presence of Grade 4 anular disruption with discographic reproduction of patients' exact low back pain. METHODS: Records of patients with low back pain who had undergone lumbar spine discography injection and post-computed tomography from June 1995 to August 1996 were reviewed. Two independent observers were asked to identify the presence of an high-intensity zone from the T12-L1 disc to L5-S1 on T2-weighted magnetic resonance images. With this data, interobserver reliability was assessed with the kappa statistic. Concordant high-intensity zone results were then compared with the Dallas Discogram rating for anular disruption and to patients' subjective pain response to discography injection. With this data, the sensitivity, specificity, and predictive values of high-intensity zone for detecting disc disruption and pain response were calculated. RESULTS: The interobserver reliability for detecting a high-intensity zone in a given disc was fair to good (kappa = 0.57; 95% confidence interval = 0.44, 0.70). The sensitivity of high-intensity zone for detecting Grade 4 anular disruption and exact pain was poor (31%) but its specificity was relatively high (90%). The positive predictive value of a high-intensity zone was low (40%) for a severely disrupted and exactly painful disc. CONCLUSIONS: The interobserver reliability of detecting a high-intensity zone and the positive predictive value of the presence of a high-intensity zone for detecting a severely disrupted and exactly painful disc were much lower than previous studies have shown. The relatively low positive predictive value may be attributable to differences in sample characteristics or procedural variations, or suggest that a high-intensity zone is not indicative of exactly painful internal intervertebral disc disruption.

Adult↗
PubMed1997

The use of intrathecal morphine for analgesia after posterolateral lumbar fusion: a prospective, double-blind, randomized study.

STUDY DESIGN: A prospective, randomized, double-blind, placebo-controlled study was undertaken to evaluate the efficacy and safety of intrathecal morphine for postoperative analgesia after posterolateral lumbar fusion. OBJECTIVES: To compare the early postoperative analgesia in patients who receive a single dose of intrathecal morphine intraoperatively with that of patients using a patient-controlled analgesia pump only. SUMMARY OF BACKGROUND INFORMATION: Although intrathecal morphine is used as an analgesic in a variety of medical and surgical conditions, very little has been published on its use after posterior lumbar spine surgery. Because the thecal sac is readily available during these procedures, the addition of a single injection of morphine before wound closure can be done with technical ease. If its efficacy and safety can be verified, then it could serve as a useful adjuvant to the postoperative analgesia regimen. METHODS: Sixty-eight consecutive patients undergoing posterolateral lumbar fusion were randomly assigned to two groups. The experimental group was injected intrathecally with morphine 30 minutes before wound closure, and the control group was similarly injected with a placebo of normal saline solution. All patients were connected to an on-demand patient-controlled analgesia pump to provide any additional necessary analgesia. Their use of the patient-controlled analgesia pump was tabulated by counting the number of demands and the actual amount of morphine delivered. Additionally, a visual analog scale was used to assess pain levels at pre-established regular intervals. RESULTS: The visual analog scale measurements were significantly lower for the intrathecal morphine group initially, but they surpassed those of the control group after 24 hours. Likewise, the number of patient-controlled analgesia pump demands and the amount of narcotic delivered initially were significantly lower in the experimental patients, but again reversed after the first postoperative day. The late rebound in pain and patient-controlled analgesia pump use did not reach statistical significance. There were no significant complications related to the analgesia. CONCLUSIONS: Intrathecal morphine can be safe and efficacious as an early postoperative analgesic after lumbar fusion when respiratory monitoring is used.

Adult↗
PubMed1995

Glenoid cysts mimicking cervical radiculopathy.

STUDY DESIGN: Patients are often referred for the evaluation of neck or radiating shoulder or arm pain who are suspected of having a possible cervical spine origin of their symptoms. Careful evaluation may show ganglion cysts of the glenohumeral joint mimicking symptoms of cervical radiculopathy. OBJECTIVES: To present a series of patients in whom cysts originating from the glenohumeral joint caused symptoms mimicking cervical radiculopathy. SUMMARY OF BACKGROUND DATA: Suprascapular nerve entrapment in the suprascapular notch by ganglion cysts from the glenohumeral joint has been described as the source of vague radicular symptoms. This paper presents a series of patients referred to a spine practice for the evaluation of cervical radiculopathy who actually had glenoid cysts mimicking cervical radiculopathy. METHODS: Three hundred forty-two patients were evaluated for cervical radiculopathy; of these, eight had glenoid cysts that were the source of the patients' symptoms. RESULTS: All eight patients had a positive shoulder impingement sign, or, in all, symptoms were temporarily relieved with intra-articular lidocaine injection. Four of the eight patients had abnormal electromyelography and nerve conduction velocity for suprascapular nerve compression. Magnetic resonance imaging of the shoulder was diagnostic in all eight patients. CONCLUSION: Proper evaluation of the shoulder must be done because it may mimic symptoms of cervical radiculopathy.

Adult↗
PubMed1994

Sacroiliac joint: pain referral maps upon applying a new injection/arthrography technique. Part I: Asymptomatic volunteers.

STUDY DESIGN: Pain pattern mapping of the sacroiliac joint in asymptomatic volunteers was investigated. Prospective evaluation of 10 volunteers who received sacroiliac joint injections was performed. The injections consisted of contrast material followed by Xylocaine. OBJECTIVES: To determine the pain referral pattern of the sacroiliac joint in asymptomatic individuals. SUMMARY OF BACKGROUND DATA: All 10 individuals experienced discomfort upon initial injection, with the most significant sensation felt directly around the injection site. Subsequent sensory examination revealed an area of hypesthesia running caudally from the posterior superior iliac spine. METHODS: Volunteers were asked to describe the nature and location of the sensation upon sacroiliac injection. Sensory examination immediately followed the injection to determine referral patterns. RESULTS: Sensory examination immediately after sacroiliac injection revealed an area of buttock hypesthesia extending approximately 10 cm caudally and 3 cm laterally from the posterior superior iliac spine. This area of hypesthesia corresponded to the area of maximal pain noted upon injection. CONCLUSION: A pain referral map was successfully generated using provocative injections into the right sacroiliac joint in asymptomatic volunteers.

Adult↗
PubMed1989

Reconstruction of the lumbar spine using AO DCP plate internal fixation.

Augmentation of lumbar spine fusion with internal fixation using pedicle screw systems has gained wide currency because it offers rigid stabilization to foster fusion healing. The AO DCP plate has been employed in Europe as a spinal implant with pedicle fixation using 6.5 mm, full-threaded cancellous bone screws with success. This report details the experience of using this device for lumbar spine fusion in a series of 46 North American patients with a mean follow-up of 1.25 years (range 1-2.5 years). Thirty-one patients had had prior lumbar spine surgery with poor outcomes, and 15 had had no prior surgery. All were treated surgically for lumbar degenerative disease with canal decompression, internal fixation with AO plates, and fusion with autologous bone grafting posterolaterally. Complications included two early and one delayed wound infection; five cases of screw loosening; three cases of screw breakage; and three cases of screw impingement upon a nerve. Results of surgery in 17 patients with failed interbody fusion included good to excellent pain relief in 59%, and solid fusion in 76%. In 14 patients with failed posterior surgery the good to excellent pain relief rate was 79%, and the fusion rate was 86%. In 15 patients undergoing primary surgery there was 89% good to excellent pain relief and a solid fusion rate of 87%. The benefits accruing from augmentation of the fusion with internal fixation using AO DCP plates are positive and justify its continued use. Complications encountered in the early experience have been significantly reduced in subsequent series, indicating the existence of a "learning curve" effect which would mandate specific training of spinal surgeons in the technique.

Bone Plates↗
PubMed1988

A reassessment of Holt's data on: "The question of lumbar discography".

This paper is a detailed critique of Holt's study entitled "The Question of Lumbar Discography." His finding of a 37% false positive rate in asymptomatic volunteers has been used to discredit lumbar discography as a valid diagnostic study in the investigation of low back pain patients with nonprolapsing disc disease of the lumbar spine. The authors show why Holt's paper should no longer be used as scientific and authoritative evidence against the use of discography by today's standards.

Back Pain↗
PubMed1987

Backache and its prevention.

Low back pain (LBP) is a symptom produced by disorders of the lumbar spine. It may be impossible to prevent all LBP, and while most episodes of acute LBP are self-limiting, the disorders producing recurrent and chronic LBP are usually incurable. The difficulties in diagnosing the disorders complicate effective management and prevention; however, prevention of spinal trauma reduces the incidence and prevalence of LBP. Effective preventive measures include the reduction of road trauma and smoking, improved vehicle seating, the control of vehicle vibrations, careful worker selection, job redesign, improved physical fitness, and the proper use of the spine in the home, at school, at work, and in sports. Frymoyer includes these and other measures in his tips to prevent LBP. Medical and paramedical professionals must be sure their investigations and treatments do not contribute to making the disorder chronic and more complex. The inappropriate use and interpretation of spinal investigations and the overzealous use of surgical procedures certainly add to the problem. An agreement on an acceptable "glossary" of lumbar terms and clinical syndromes is needed together with a new research emphasis on prevention and a continuation of research efforts in epidemiology, etiology, and management of LBP. Effective public education is vital, so that everyone is aware of the causes and methods of prevention of LBP. Discussion on the "20th-century epidemic of LBP" may be concluded on an optimistic note by citing White, who considers most LBP to be preventable and controllable with simple measures, reinforcable through public education, which can do for LBP what has been done in the field of dental hygiene.

Back Pain↗
PubMed1984

An update on the early management of traumatic paraplegia (nonoperative and operative management).

Both the spinal cord physician and the spinal surgeon must be fully cognizant of the alterations of functions in multiple systems of the body caused by a spinal cord injury. Complications can easily arise, particularly within the respiratory, urinary, and integumentary systems. Most are preventable if the medical and nursing staff are sufficiently knowledgeable to anticipate them and if the necessary equipment and facilities are available. Regionalization of care with early referral to a spinal cord injury center has become a cost-effective way to manage these patients. Only if their medical needs are met and complications are prevented will surgery, performed to allow early mobilization, really accomplish the desired result. This update reviews the current medical and surgical points of view concerning diagnosis, fracture classification, spinal stability, reduction and stabilization of the fracture deformity, and spinal canal decompression.

Contracture↗
PubMed1980

Electromyographic activity in paraspinal musculature in patients with idiopathic scoliosis before and after Harrington instrumentation.

Ten patients with idiopathic scoliosis underwent electromyographic (emg) examination before and after Harrington instrumentation and fusion. Each patient had a normal emg preoperatively. At 3 weeks all 10 demonstrated spontaneous activity consistent with denervation, and voluntary activity was absent or markedly reduced. By 3 months and in some cases 6 months, denervation was significantly reduced or absent; voluntary activity had also reappeared and in most cases was equal to preoperative intensity. This rapid reversal of denervation after surgery within the paraspinal muscles in a young female population with no underlying disease suggests that interpretation of any postoperative emg should include considerations such as the time since surgery, the age of the patient, and the extent of preoperative pathology. No evidence was gained from this study that extensive posterior spinal surgery itself interfered significantly with paraspinal muscle function after 3 to 6 months.

Electromyography↗
PubMed1975

Discography in paralytic scoliosis.

Observations are made on the progressive alterations of the intervertebral disc in paralytic scoliosis, demonstrated by discography.

Adolescent↗
PubMed1975

Paralytic pelvic obliquity. Its prognosis and management and the development of a technique for full correction of the deformity.

Thirty-nine patients with post-poliomyelitic scoliosis and pelvic obliquity were treated and followed for up to four years. The dominant pathological mechanism causing the pelvic obliquity was trunk-muscle imbalance. The natural history of untreated pelvic obliquity is progression, leading ultimately to dislocation of the hip. The functional abilities of the patient are then severely restricted. Our aim in treatment was to obtain the maximum possible correction of pelvic tilt and so to prevent subluxation of the femoral head. Total correction was obtained in fifteen patients; no loss of correction was seen in twenty-four patients. The best results were achieved by preliminary traction, Dwyer instrumentation distally to the fifth lumbar vertebra, and extensive posterior fusion extendind distally to the sacrum.

Female↗
PubMedDate not supplied

Stablization of the spine in the surgical treatment of severe spinal tuberculosis in children.

This is a 5- to 10-year survey of 160 children, all with severe surgically-treated spinal tuberculosis. The treatment consisted of: anterior spinal fusion alone, anterior with posterior fusion, posterior fusion alone and posterior with anterior fusion. The results indicate that in the less severe cases, where an abscess is not evident on plain radiographs, psoterior fusion alone can be of value in the growing spine. In severe cases, especially where an abscess is seen, the combined approaches give the best results. The risk of posterior fusion alone is an unsatisfactory, long term neurological outcome in too many patients. The combined procedure of anterior fusion with posterior fusion is the treatment of choice for all immature spines with this disease.

Abscess↗
PubMedDate not supplied

A multidisciplinary approach to chronic low-back pain in Western Australia.

Fifty patients with chronic low-back pain were subjected to extensive medical, psychiatric, and psychosocial assessment by a comprehensive Low Back Pain Clinic. Most patients were found to have easily identifiable environment factors which influenced the persistence of the symptomatology. All patients were significantly functionally impaired, and whilst neurologic findings were uncovered in only 12 patients, most had restricted movement of the lumbar spine. The initiating cause of the low-back pain was usually from a minor injury or no injury at all. Thirty-two patients were given psychiatric diagnoses, but only one patient was thought to warrant psychiatric treatment. Whilst some were considered to be candidates for limited further conservative treatment, only two were subjected to further surgery (one fusion, one posterior facet rhizotomy). Only nine were admitted to an inpatient behavior modification program, and the results of this effort were modest. The major benefit was seen to be the definitive diagnosis, prognosis, and medical and social planning which was given to all 50 patients upon conclusion of the assessment. The assessment proved to be of benefit to the patient, the referring doctor, the team itself, as well as all other interested parties, such as his family, insurance company, and lawyer.

Adult↗